[ CVE-2021-34473 · Published 14 Jul 2021 ]
Microsoft Exchange Server Remote Code Execution Vulnerability
Exploited · CISA KEV CVSS 9.1
EPSS 100%Fix available
[ Why it matters ]Priority signals
- Exploited in the wild: on CISA's Known Exploited Vulnerabilities list since 2021-11-03
- Known to be used in ransomware campaigns
- EPSS: 100% chance of exploitation in the next 30 days (higher than 100% of CVEs)
- Critical severity: CVSS 9.1
[ Description ]Official description
Microsoft Exchange Server Remote Code Execution Vulnerability
CISA: Microsoft Exchange Server contains an unspecified vulnerability that allows for remote code execution.
[ Fixes ]Fixes and patches
CISA required action (US federal deadline 17 Nov 2021): Apply updates per vendor instructions.
- Patch on msrc.microsoft.comVendor patch or bulletin · NVD · Reference tagged 'Patch' by NVD
- Patch on portal.msrc.microsoft.comVendor patch or bulletin · NVD · Reference tagged 'Patch' by NVD
[ References ]References
- msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34473PatchVendor Advisory
- packetstormsecurity.com/files/163895/Microsoft-Exchange-ProxyShell-Remote-Code-Executio…ExploitThird Party AdvisoryVDB Entry
- portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34473PatchVendor Advisory
- www.zerodayinitiative.com/advisories/ZDI-21-821Third Party AdvisoryVDB Entry
- www.cisa.gov/known-exploited-vulnerabilities-catalogUS Government Resource